Appearance
The breed standard of the Modern Siamese indicates an elegant, slim, stylish, flexible and well muscled body. Its head is triangular shaped, with a thin snout. The eyes are almond-shaped and oblique, the ears large and thin. It has a long neck, body and tail. The fur is short, glossy, fine, soft, tight and adhered to the body. The Siamese is characterized by its typical pointed color scheme.
The pointed pattern is a form of partial albinism, resulting from a mutation in tyrosinase, an enzyme involved in melanin production. The mutated enzyme is heat-sensitive; it fails to work at normal body temperatures, but becomes active in cooler areas of the skin. This results in dark coloration in the coolest parts of the cat's body, including the extremities and the face, which is cooled by the passage of air through the sinuses. All Siamese kittens, although pure cream or white at birth, develop visible points in the first few months of life in colder parts of their body. By the time a kitten is four weeks old the points should be clearly distinguishable enough to recognize which color they are. Siamese cats tend to darken with age, and generally adult Siamese living in warm climates have lighter coats than those in cool climates. Originally the vast majority of Siamese had seal (extremely dark brown, almost black) points, but occasionally Siamese were born with blue (a cool grey) points, genetically a dilution of seal point; chocolate (lighter brown) points, a genetic variation of seal point; or lilac (pale warm gray) points, genetically a diluted chocolate. These colors were at first considered "inferior" seal points, and were not qualified for showing or breeding. All of these shades were eventually accepted by the breed associations, and became more common through breeding programmes specifically aimed at producing these colors. Later, outcrosses with other breeds developed Siamese-mix cats with points in other cat colors and patterns including flame point, lynx (tabby) point, and tortoise-shell ("tortie") point.
In the United Kingdom, all pointed Siamese-style cats are considered to be part of the Siamese breed. In the United States, the major cat registry, the Cat Fanciers' Association, considers only the four original colourations as Siamese: seal point, blue point, chocolate point, and lilac point. Oriental cats with colourpoints in colours or patterns aside from these four are considered Colorpoint Shorthairs in the American cat fancy.
Many Siamese cats from Thailand had a kink in their tails but over the years this trait has been considered to be a flaw and breeders have largely eradicated it, although it persists among street cats in Thailand. Many early Siamese were cross-eyed to compensate for the abnormal uncrossed wiring of the optic chiasm, which is produced by the same albino allele that produces colored points. Like the kinked tails, the crossed eyes have been seen as a fault and through selective breeding, the trait is far less common today.
The Thai or Traditional Siamese shares some features with the Modern Siamese (e.g., the color pattern) but differs from it by their rounded shapes. It has a more compact body and an applehead, with full and rounded cheeks, shorter snout, ears high, but not huge. The eyes are medium to slightly large, a very full almond shape, but not oriental.
Temperament
Siamese are affectionate and intelligent cats, renowned for their social nature. Many enjoy being with people and are sometimes described as "extroverts". As there are extrovert Siamese, there also are some that have very sensitive and nervous temperaments. Those individuals may not easily adapt to the changes of environment or to strangers. They do have a great need for human companionship. Often they bond strongly to a single person. Most Siamese like to have other sociable cats for company and do not thrive as only cats owned by people who are gone much of the day. Siamese are extremely vocal, with a loud, low-pitched voice – known as "Meezer", from which they get one of their nicknames – that has been compared to the cries of a human baby, and persistent in demanding attention. These cats are typically active and playful, even as adults.
The social orientation of Siamese cats may be related to their lessened ability to live independent of humans. Siamese coat colouration is appealing to humans, but is ineffective for camouflage purposes. They are less active at night than most cats, possibly because their blue eyes lack a tapetum lucidum, a structure which amplifies dim light in the eyes of other cats. The mutation in the tyrosinase also results in abnormal neurological connections between the eye and the brain. Unlike many other blue-eyed white cats, Siamese cats do not have reduced hearing ability. The deafness that sometimes occurs in completely white cats is a result of the genetics that causes the loss of pigment cells in the skin, which has nothing to do with the tyrosinase gene defect that causes Siamese color. Regardless, being dependent on humans may have been a survival trait for ancestors of the Siamese.
